So far self-driving cars have been pretty good at avoiding crashes, although that has partly been due to human intervention, but on Valentine’s Day last month Google’s autonomous car caused a minor crash, coming off worse for wear with ‘sustained body damage’.

In a report filed to the US DMV after the incident, Google stated that its Lexus-model AV “signaled its intent to make a right turn on red onto Castro St” before it “had to come to a stop and go around sandbags positioned around a storm drain that were blocking its path.”

“The Google AV began to proceed back into the center of the lane to pass the sand bags. A public transit bus was approaching from behind. The Google AV test driver saw the bus approaching in the left side mirror but believed the bus would stop or slow to allow the Google AV to continue.”

Needless to say, three seconds later the AV and the bus collided in a slow speed crash. Nobody was hurt, though Google did release a statement to The Verge afterwards explaining the root cause of the problem:

“Our test driver, who had been watching the bus in the mirror, also expected the bus to slow or stop. And we can imagine the bus driver assumed we were going to stay put. Unfortunately, all these assumptions led us to the same spot in the lane at the same time. This type of misunderstanding happens between human drivers on the road every day.”

With the likes of Tesla, Volvo and maybe even Apple all looking to get their autonomous cars on the road in the near future we could be reading more reports of these incidents in the future. These pose difficult problems for driverless car manufacturers, the most extreme of which explore further in the March issue of BBC Focus magazine – could your driverless car choose to kill you?